<template>
  <div>
    <p>请选择你要购买的书籍</p>
    <ul>
      <li v-for="(item, index) in arr">
        {{ item.name }} <button @click="mai(index)">购买</button>
      </li>
    </ul>
    <table border="1" width="500" cellspacing="0">
      <tr>
        <th>序号</th>
        <th>书名</th>
        <th>单价</th>
        <th>数量</th>
        <th>合计</th>
      </tr>
      <tr v-for="item in arr">
        <td>{{ item.id }}</td>
        <td>{{ item.name }}</td>
        <td>{{ item.price }}</td>
        <td>{{ item.count }}</td>
        <td>{{ item.price * item.count }}</td>
      </tr>
    </table>
    <p>总价格为:{{ num }}</p>
  </div>
</template>

<script>
export default {
  data() {
    return {
      arr: [
        { id: 1, name: "水浒传", price: 107, count: 0 },
        { id: 2, name: "西游记", price: 192, count: 0 },
        { id: 3, name: "三国演义", price: 219, count: 0 },
        { id: 4, name: "红楼梦", price: 178, count: 0 },
      ],
    };
  },
  computed: {
    num() {
      return this.arr.reduce((a, b) => {
        return (a += b["price"] * b["count"]);
      }, 0);
    },
  },
  methods: {
    mai(index) {
      this.arr[index].count++;
    },
  },
};
</script>